This invention relates in general to shift levers for manually operable vehicle transmissions and in particular to a noise and vibration dampening connector for a two-piece transmission shift lever assembly.
In most vehicles, a transmission is provided in the drive train between the engine and the driven wheels. As is well known, the transmission includes a plurality of gears which are selectively engaged to provide a plurality of speed reduction gear ratios between the input and the output of the transmission. A control member within the transmission is moved by a driver of the vehicle throughout a plurality of gear ratio positions for selecting the desired speed reduction. As a result, acceleration and deceleration of the vehicle can be achieved in a smooth and efficient manner.
In many smaller vehicles, such as automobiles, the transmission functions automatically to move the control member without any physical intervention by the driver of the vehicle. However, such automatic transmissions are typically not used in larger vehicles, such as trucks, because of their increased size and expense. Such larger vehicles are, therefore, often provided with manually operable transmissions. In a manually operable transmission, the shifting of the control member is accomplished by physical movement of the control member by the vehicle driver.
In order to move the control member among the various gear ratio positions in a manual transmission, a manually operable shift lever assembly is usually provided. The shift lever assembly includes a lower member, which extends downwardly within the transmission into engagement with the control member. The shift lever assembly further includes an upper member, which extends upwardly into a driver compartment of the vehicle for convenient grasping and manipulating by the vehicle driver. Thus, when the upper member of the shift lever assembly is moved by the vehicle driver, the lower member thereof is moved within the transmission. By properly moving the upper member of the shift lever assembly, the vehicle driver can position the control member of the transmission so as to select any one of the plurality of gear ratios for use.
When the vehicle is operated, it has been found that the transmission and other components of the drive train of the vehicle vibrate to a certain extent. In addition, vibrations are generated by the vehicle engine itself during operation. All of such vibrations can be sensed by the vehicle driver as undesirable noise. To reduce the amount of this undesirable noise, the driver compartment of the vehicle is typically lined with acoustical insulating material. Unfortunately, the upper member of the shift lever assembly must extend upwardly from the transmission into the driver compartment for convenient use, as described above. As a result, the shift lever assembly can function to transmit these vibrations into the driver compartment, thus defeating the acoustical insulation.
To address this, it is known to provide a dampening mechanism in the shift lever assembly for reducing the amount of vibration and noise transmitted therethrough from the engine and transmission to the driver compartment of the vehicle. To accomplish this, the shift lever assembly is divided into upper and lower shift lever members, and a noise and vibration dampening connector is connected therebetween. A typical vibration and noise dampening connector includes one or more elastic dampening members which are disposed within a cylindrical sleeve connected between the upper and lower shift lever members. A number of such vibration and noise dampening connectors are known in the art. However, known vibration and noise dampening connectors have been found to be unduly complex and expensive in construction and assembly. Consequently, it would be desirable to provide an improved structure for a noise and vibration dampening connector for a multi-piece transmission shift lever assembly which is simple and inexpensive in construction and assembly.